1. Field of the Invention
The present invention relates to a camera, and more particularly to a camera in which it is prevented to set the first frame while a lid of a cassette chamber is open.
2. Description Related to the Prior Art
In the market, there is a camera adopting an advanced photo system, in which an IX 240 film cassette (hereafter film cassette) is used. In a cassette housing of the film cassette, a photo film is entirely contained and rolled about a spool. When the spool is rotated, the photo film is advanced or rewound. A film passage mouth formed on the cassette housing for feeding the photo film is opened and closed with a cassette door.
After loading the film cassette in a cassette chamber of the camera, the lid of the cassette chamber is closed. Thereby the cassette door is opened with a member in the camera. Then a feed motor is driven at a predetermined time (for example 4.5 seconds) to rotate the spool in an advancing direction for setting the first frame to an exposure aperture. Thus the photo film is advanced from the film passage mouth. When the first frame of the photo film is set to an exposure aperture, the feed motor stops.
In the normal camera, sensors are provided to detect for the loading of the film cassette and the lid of the cassette chamber. Based on signals of the sensors, the photo film is advanced to set the first frame to the exposure aperture. The camera produced in a low cost, however, cannot be provided with the sensor. Accordingly, there are many types of the camera which begins the first frame to set to the exposure aperture corresponding to depress of the shutter release button. Sometimes, there is a user who forgets to unload the film cassette from the cassette chamber after rewinding all of the photo film in the film cassette, and depresses the shutter release button. Then the photo film in the film cassette is advanced again and double exposures may be carried out.
This problem is solved in a camera disclosed in a Japanese Patent Laid-open Publication No. 9-73127. The camera has a shutter lock member, a holder and an unlock mechanism. The shutter lock member prohibits operating a shutter release button, corresponding to operation of a rewinding button to rewind the photo film. The holder holds the shutter lock member in a shutter release button lock position. Corresponding to opening the lid of the film cassette, the unlock mechanism makes the holder releasing the shutter lock member so as to unlock the shutter release button without jamming.
In the camera described above, the shutter release button is locked on rewinding the photo film and after completion thereof with the cassette door opened. However, when the lid of the cassette chamber is not perfectly closed at loading the film cassette therein, the shutter release button is not locked. In this situation, while the cassette door is closed, the shutter release button is sometimes depressed, and the spool is rotated in an advancing direction. Therefore, the photo film jams in the film cassette, which damages the photo film and makes unusable. Further, as the spool can not be rotated, a large load causes a failure of an advancing system of the camera.
An object of the present invention is to provide a camera in which the photo film is prevented from jamming in the cassette housing.
Another object of the present invention is to provide a camera in which it is prevented to set the first frame to an exposure aperture while a lid of the cassette chamber is not closed.
In order to achieve the object and the others, in a camera of the present invention, a door actuate mechanism closes and opens a cassette door of a film cassette loaded in a cassette chamber, and a shutter lock mechanism locks and unlocks a shutter release button, interlocking with open and close of a lid of the cassette chamber. The shutter lock mechanism is provided with a shutter lock member which is set in a lock position when the lid is opened, and in an unlock position when the lid is closed. In the lock position, the shutter lock member inserts in a moving path of the shutter release button to prevent the depress thereof. In the unlock position, as the shutter lock member is retracted from the moving path of the shutter release button such that the shutter release button may be depressed, and as the cassette door is opened, a leading end of the photo film may be advanced from the film cassette without jamming.
According to the camera of the present invention, even though having a simple structure, the shutter release button is not depressed to set the first frame to the exposure aperture when the lid is opened. Therefore, the photo film never jams in the film cassette and is not damaged, and the camera does not have failure.